- Interactions between biocide cationic agents and bacterial biofilms
-
The resistance of bacterial biofilms to physical and chemical agents is attributed in the literature to various interconnected processes. The limitation of mass transfer alters the growth rate, and physiological changes in the bacteria in the film also appear. The present work describes an approach to determination of the mechanisms involved in the resistance of bacteria to quaternary ammonium compounds (benzalkonium chloride) according to the C-chain lengths of those compounds. For Pseudomonas aeruginosa CIP A 22, the level of resistance of the bacteria in the biofilm relative to that of planktonic bacteria increased with the C-chain length. For cells within the biofilm, the exopolysaccharide induced a characteristic increase in surface hydrophilicity. However, this hydrophilicity was eliminated by simple resuspension and washing. The sensitivity to quaternary ammonium compounds was restored to over 90%. Staphylococcus aureus CIP 53 154 had a very high level of resistance when it was in the biofilm form. A characteristic of bacteria from the biofilm was a reduction in the percent hydrophobicity, but the essential point is that this hydrophobicity was retained after the biofilm bacteria were resuspended and washed. The recovery of sensitivity was thus only partial. These results indicate that the factors involved in biofilm resistance to quaternary ammonium compounds vary according to the bacterial modifications induced by the formation of a biofilm. In the case of P. aeruginosa, we have underlined the involvement of the exopolysaccharide and particularly the three-dimensional structure (water channels). In the case of S. aureus, the role of the three-dimensional structure is limited and drastic physiological changes in the biofilm cells are more highly implicated in resistance.
- Campanac,Pineau,Payard,Baziard-Mouysset,Roques
-
-
Read Online
- Solvatochromism in aqueous micellar solutions: Effects of the molecular structures of solvatochromic probes and cationic surfactants
-
Solvatochromic behavior of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)- 1-phenolate (RB); 1-methyl-8-oxyquinolinium betaine (QB); sodium 1-methyl-8- oxyquinolinium betaine-5-sulfonate (QBS); and 1-methyl-3-oxypyridinium betaine (PB) was studied spectrophotometrically in micellar solutions of the following cationic surfactants: cetyltrimethylammonium chloride, cetyldimethylbenzylammonium chloride, dodecyltrimethylammonium chloride, and dodecyldimethylbenzylammonium chloride. Microscopic polarity of water at the (average) solubilization site of the solvatochromic probe, E(T) in kcal mol- 1, was calculated from the position of the longest-wavelength absorption band of the probe. The visible spectrum of PB, the most hydrophilic probe, is not affected by surfactants because it is not included in the micellar pseudo phase. For the other three solvatochromic probes, calculated E(T) values depend on the structures of both the probe and the surfactant, namely, its headgroup and long-chain alkyl group. RB, the most hydrophobic probe, samples a much lower microscopic polarity than QB and QBS because it penetrates deeper into the cationic micelle. This conclusion has been confirmed by 1H NMR. Polarities measured by (zwitterionic) QB and (anionic) QBS differ because the latter probe exchanges with the surfactant counterion. Calculated E(T) values refer to micelle-bound probes and are, therefore, different from those reported in the literature, typically determined at [surfactant] ≤ 0.05 mol L-1. Effective water concentrations at the solubilization sites of these solvatochromic probes has been calculated by using as references mixtures of water with each the following organic solvents: n-propanol and dioxane (RB); ethanol, n-propanol, acetonitrile and dioxane (QB and QBS).
- Novaki, Luzia P.,El Seoud, Omar A.
-
-
Read Online
- Kinetic Features of an Intraresin Reaction
-
The kinetic features of the intraresin displacement by pendant ammonium acetate groups on chloromethylated polystyrene have been investigated as a function of temperature, swelling solvent, and cross-link density.In all cases, intraresin displasement proceeds with a rapid initial rate folowed by a very slow second stage; the latter represents that fraction of reactant which become "kinetically isolated".The free energy of activation for the first stage, under the various swelling conditions used, lies in the range 24.4-26.8 kcal mol-1, which is similar to that found for analogous homogeneous reactions.The absolute rates measured for the homogeneous and the initial intraresin displacement in dioxane were similar; with n-hexane and toluene as solvents, polymeric rates were considerably slower than those of their homogeneous counterparts.Intraresin displacement was rapid even when a poor swelling solvent (n-hexane) was used.As the rate of intrapolymeric reaction decreased (through a decrease in temperature, increase in cross-link density, or change in solvent) the percent of "kinetically isolated" sites increased.
- Kim, Bong,Kirszensztejn, Piotr,Bolikal, Durgadas,Regen, Steven L.
-
-
Read Online
- Benzalkonium chloride preparation method
-
The invention discloses a benzalkonium chloride preparation method, which comprises: (1) carrying out a salt formation reaction on a fatty alkyl dimethyl tertiary amine and benzyl chloride in an organic solvent at a temperature of 30-70 DEG C to obtain fatty alkyl dimethyl benzyl ammonium chloride, wherein the fatty alkyl is dodecyl, tetradecyl or hexadecyl, and the organic solvent is one or a plurality of materials selected from methanol, ethanol, n-propanol, isopropanol, acetone and acetonitrile; and (2) in an organic solvent, crystallizing the mixture containing two or three fatty alkyl dimethyl benzyl ammonium chlorides prepared in the step (1). According to the present invention, the preparation method has advantages of simple process and high yield, wherein the yield can achieve morethan 90%; the content of the related substance is low, and the purity is high, and can achieve more than 99%; the water content is low; and the product has good appearance and simple post-treatment effect, can meet the requirements of various pharmacopoeia, and is suitable for the industrial production of pharmaceutical-grade benzalkonium chloride.
- -
-
Paragraph 0035-0036; 0045-0048
(2019/04/26)
-
- Fatty alkyl dimethyl benzyl quaternary ammonium salt synthesis method
-
The invention discloses a fatty alkyl dimethyl benzyl quaternary ammonium salt preparation method, which comprises: carrying out a salt formation reaction on fatty alkyl dimethyl tertiary amine and abenzyl halide in an organic solvent at a temperature of 30-70 DEG C, wherein R in the fatty alkyl tertiary amine is C6H13-C22H45, the halogen in the benzyl halide is chlorine, bromine or iodine, and the organic solvent is one or a plurality of materials selected from methanol, ethanol, n-propanol, isopropanol, acetone and acetonitrile. According to the present invention, the yield of the preparation method is high, and can reach more than 90%; the purity is high, and can achieve more than 99%; the water content is low; the product has good appearance and simple post-treatment effect; and the method can reduce the energy consumption, and is suitable for industrial production.
- -
-
Paragraph 0047-0050; 0071
(2019/04/26)
-
- Benzalkonium chloride monomer synthesis technology
-
The invention relates to the technical field of fine chemicals, and more specifically relates to a benzalkonium chloride monomer synthesis technology. The synthesis technology comprises the following steps: (1) according to a formula, weighing fatty alkyl dimethyl tertiary amines, benzyl chloride, and ethyl acetate; (2) adding ethyl acetate into a glass lined reactor, pumping fatty alkyl dimethyl tertiary amines and benzyl chloride into a head tank, starting the stirring device of the reactor, dropwise adding fatty alkyl dimethyl tertiary amines and benzyl chloride into the reactor at a room temperature according to a same ratio; (3) heating the reactor to a temperature of 70 to 100 DEG C, and maintaining the temperature to carry out reactions for 7 to 10 hours; (4) starting circulating cooling water to cool the products to the room temperature until crystals are precipitated completely; (5) taking out the crystals, subjecting the crystals to vacuum suction filtration, during the suction filtration process, washing the crystals by ethyl acetate for 2 to 5 times, and saving the filter cakes; and (6) adding ethyl acetate into the filter cakes, carrying out re-crystallization, and after the crystals are completely precipitated, drying the crystals. The production cost is low and the purity of prepared benzalkonium chloride is high.
- -
-
Paragraph 0018; 0023
(2017/09/01)
-
- A synthetic method of a benzalkonium chloride mixture
-
The invention relates to the technical field of organic synthesis, and particularly relates to a synthetic method of a benzalkonium chloride mixture. The method includes (1) weighing alkyl dimethyl tertiary amine, a metal or nonmetal halide, benzyl chloride and an organic solvent separately according to a ratio; (2) dissolving the alkyl dimethyl tertiary amine and the metal or nonmetal halide into the organic solvent according to a ratio to obtain a mixture system, putting the mixture system in a hydrothermal boiler and raising the temperature of the mixture system to 50-80 DEG C; (3) adding dropwise the benzyl chloride into the mixture system in the step (2) under continuous stirring, with the adding speed being 30-40 drops per min, stirring the mixture system until the dropwise addition is finished, and allowing the obtained mixture system to stand for 3-8 h to obtain benzalkonium chloride single crystals; and (4) subjecting the mixture system in the step (3) to suction filtration, and performing washing operation and recrystallization to obtain the benzalkonium chloride. Compared with traditional processes, the metal or nonmetal halide is adopted as an additive of the method, can promote benzalkonium chloride generation from a reaction of the alkyl dimethyl tertiary amine and the benzyl chloride, and increases the conversion ratio of reactants; and a benzyl chloride dropwise addition manner is adopted by the method, thus reducing benzyl chloride volatilization, allowing the benzyl chloride to be completely reacted as soon as the benzyl chloride is added into a solution, and increasing the conversion ratio of the reactants.
- -
-
Paragraph 0019; 0020; 0023; 0024
(2017/08/30)
-
- DENTAL ORAL COMPOSITION
-
A dental composition for oral use, containing a phosphorylated saccharide (a), a polyphosphoric acid and/or a salt thereof (b), and a cationic bactericidal agent (c), wherein a ratio of a total amount of the phosphorylated saccharide (a) and the polyphosphoric acid and/or a salt thereof (b) contained to an amount of the cationic bactericidal agent (c) contained, i.e. {(a)+(b)}/(c), is from 0.05 to 20 in a weight ratio. The dental composition for oral use of the present invention can be suitably used for an oral cavity cleaning agent, including dentifrice agents such as a paste dentifrice agent, a powder dentifrice agent, and a liquid dentifrice agent, a mouse-wash agent, a troche, a tablet, a cream, an ointment, a bonding agent, a mouth spray, a coating agent to tooth surface or a dental prosthetic, a hypersensitive inhibitor, a therapeutic agent for periodontal diseases, that is applied to a periodontal pocket, wet tissue for oral cavity care, an oral refreshing agent, chewing gum, or a gargling agent, or the like.
- -
-
-
- Quaternization reaction of some N,N-dimethylalkylamines with benzyl chloride
-
The parameters which influence the quaternization reaction of some N,N-dimethylalkylamines of RN(CH3)2, type (R = octyl, decyl, dodecyl, tetradecyl and hexadecyl) with benzyl chloride were studied. By thermogravimetric analyses, the kinetic parameters, the reaction order, "n", and the activation energy, "Ea", of the thermal decomposition of the quaternary salts prepared in this study, were established.
- Avram, Ecaterina
-
-
- Kinetics of the pH-independent hydrolysis of 4-nitrophenyl chloroformate in aqueous micellar solutions: Effects of the charge and structure of the surfactant
-
The pH-independent hydrolysis of 4-nitrophenyl chloroformate in the presence of aqueos micelles of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkyltrimethylammonium chlorides, alkyldimethylbenzylammonium chlorides (alkyl group = cetyl and dodecyl) and polyoxyethylene (9) nonylphenyl ether was studied spectrophotometrically. The observed rate constants, kobs, decrease in the following order: cationic micelles > bulk water > non-ionic micelles > anionic micelles. Surfactant-substrate association constants, Ks, were determined from the dependence of kobs on surfactant concentration, and were found to be only slightly dependent on the charge of the surfactant and, for similarly charged micelles, on the length of their hydrophobic tail. A 1H NMR study of the solubilzation of a model compound, 4-nitrophenyl chloroacetate, showed that all surfactant segments are affected by the solubilizate and the effect is more pronounced toward the middle of the hydrocarbon chain. The average solubilization site of the acetate ester does not depend on the charge of the micelle or the length of the surfactant hydrophobic tail. Micellar effects on observed rate constants are analyzed in terms of a 'medium' effect and an 'electrostatic' effect. The lower microscopic polarity at the reaction site retards the reaction, whereas electrostatic interactions of the polar transition state with the charged interface result in a rate decrease by anionic micelles and a rate enhancement by cationic micelles. Copyright
- Possidonio, Shirley,Siviero, Fabio,El Seoud, Omar A.
-
p. 325 - 332
(2007/10/03)
-
- Proton NMR Studies on the Structure of Water in Ionic and Nonionic Water-in-Oil Microemulsions
-
The structure of water present in water-in-oil microemulsions of anionic magnesium bis(2-ethylhexyl) sulfosuccinate in C6D6, cationic cetyldimethylbenzylammonium chloride in C6D6, cetyldimethyl-3-phenylpropylammoniurn chloride in chlorobenzene, and nonionic polyoxyethylene (4) dodecyi ether in n-heptane was probed by 1H NMR. Chemical shifts of solubiiized H2O-D2O, and of surfactant discrete protons were determined, at fixed [water]/[surfaciant] ratios, as a function of the deuterium content of solubiiized water. Chemical shift data were used ID calculate the so called "fractionation factor", φ, of the aggregate-solubilized water. Calculated φ for the different systems are unity, showing that micellar water, although different from bulk water, does not seem to coexist in "layers" of different degrees of structure, as suggested, e.g., by the two-state water solubilization model. VCH Verlagsgesellschaft mbH, 1996.
- El Seoud, Omar A.,Okano, Laura T.,Novaki, Luzia P.,Barlow, Graham K.
-
p. 1147 - 1152
(2007/10/03)
-
- Acid-base equilibria of hydrophilic indicators in water-in-oil microemulsions
-
The apparent pKa values of the positively charged, hydrophilic indicators 2-hydroxy-5-bromo-trimethylanilinium chloride (HBTC) and 2-hydroxy-5-nitro-trimethylanilinium chloride (HNTC) in the presence of water-in-oil microemulsion of the surfactants benzylcetyldimethyl ammonium chloride (BCDC) in benzene and polyoxyethylene (4) dodecyl ether (Brij-30) in heptane were determined spectrophotometrically. The experimental variables were the type of buffer (benzimidazole, phosphate, and tris) and the ratios [water]/[surfactant] and [buffer]/[surfactant]. It is shown that: a) the indicators are confined within the second hydration shell of the nanodroplet, i.e. are not adsorbed at the water/oil interface; b) the use of the starting pH values of the buffer solutions, i.e., those measured outside the micellar domain, to calculate the micellar pKa values of the indicators is inadequate; c) buffer-independent micellar pKa values can be obtained if the starting pHs of the buffer solutions were corrected for ion exchange with the counter-ion of the positively charged surfactant, and for the lower polarity of the micelle-solubilized water (relative to bulk water).
- Chinelatto,Fonseca,Kiyan,El Seoud
-
p. 882 - 887
(2007/10/02)
-